The selection of relevant information from cluttered natural environments for further processing is one of the most fundamental cognitive abilities for guiding behavior. This becomes strikingly clear when attentional selection mechanisms fail, such as in individuals afflicted with ADHD, visuo-spatial hemineglect that is often observed following stroke, and schizophrenia. Converging evidence from physiology and functional brain imaging studies reveals that selective attention modulates neural activity at multiple processing stages within the visual system and beyond. This is a continuation project of our grant "Mechanisms of attention in the human visual cortex" (1 RO1-MH64043). Work during the previous funding period has characterized attentional functions of the human lateral geniculate nucleus (LGN) and visual cortical areas. These and other studies indicate that visual selective attention can be considered a multilevel selection process mediated by a distributed network of subcortical and cortical brain areas. The present application extends this work to investigate interactions of neural processing between the visual system and the fronto-parietal attention network with hypotheses derived from biased competition theory. The long-term goal of this research program is to identify the neural mechanisms underlying visual selective attention in the primate brain. This goal is pursued in our laboratory in a multi-modal methods approach that includes functional magnetic resonance imaging (fMRI) and behavioral measures in humans and monkeys, and invasive electrophysiology in monkeys. In the present application, we focus on attention mechanisms operating in the human brain using innovative high- and super-resolution fMRI methods. We propose to study attentional modulation of the magno- and parvocellular LGN (SA #1), influences of perceptual organization on biased competition (SA #2), and higher-order control of selection (SA #3) across the neural architecture that subserves visual attention. The proposed research is aimed at advancing our understanding of the neural mechanisms and the network architecture that mediates attentional functions in the human brain. Progress in understanding the basic mechanisms of selective attention is a first necessary step in developing effective treatment strategies for attentional deficits.